Heathrow Airport Power Failure Disaster

Possible terrorist attack...

..."Firefighters were called to a high-voltage substation just after 11:20 p.m. Thursday local time to find a transformer with 25,000 liters of cooling oil fully alight, the London Fire Brigade said in a statement. The fire was under control by 6:28 a.m."...

• How long it will last: Heathrow will remain closed until 11:59 p.m. Friday, the airport said in a statement, but significant disruptions are expected to continue in the coming days.
• What police say: The counterterrorism command of London’s Metropolitan Police is leading the investigation, given the impact on “critical national infrastructure,” police said. But there is “currently no indication of foul play.”

Yes it certainly seems possible a lack of proper maintenance could be the cause...

I've gone to Google maps to see what the situation is and am immediately struck by how small the substation is, (see: 12, North Hyde Gardens, Hayes), how vulnerable the transformers are - even I could climb over the fence or lob a satchel full of 'nasties' onto the structure!

Across the road from the substation is the demolished site of the old Nestle factory and guess what they have built there, 4 new warehouses including a Data Centre, (Unit 1) which has 10.2MVa power capacity, these units are already in operation 24/7 so the increased loading was probably the last straw!

So this small substation is supposed to supply 67,000 houses, a new 10.2MVa Data centre AND Heathrow Airport ??? What do the experts think will happen.

Thankfully they have managed to patch in power from surrounding areas and the airport is fully operational, let's hope the breakdown hasn't screwed up the computers in the airport which are 'fragile' at the best of times.

I did read (BBC?) that there are two substations feeding Heathrow, with 100% redundancy (i.e. the whole airport can run of either substation A or substation B). I also recall that, to be certified as an international airport, most countries require a further back-up system such as a generator that can supply the mission- and safety critical systems (tower, runway lights, fire control, navigation, etc.) in the event of both utility infeed being non-functional. However, that just ensures safety and the airport will come to halt quickly, as passenger services, air-conditioning, baggage handling, tenants, shops, etc. is not catered for.

It may be that the automatic changeover to "Substation B" did not happen? The idea is that the genset only has to keep things going for the short bit of time until the second infeed is energised and all equipment restarted (a process in itself).

Or sometimes a common piece of equipment is damaged - bad design (December 18, 2017 USA Today reported a power interruption at Atlanta Airport. When the airport was constructed, the utility power cables and the emergency power cables were routed through the same tunnel. ").

Would be interesting to see the results of both inquiries (the substation failure, and how Heathrow handled it).

Europeans traditionally have been slow to adopt the application of the sudden pressure relay or sudden pressure protective device to instantly de-energize an oil filled transformer when the gas bubble that accompanies an arcing fault is formed. These faults are very devastating and fast to devolve into a major fire.

The sudden pressure protection has limited the occurrence of a substation fire such as this significantly. Of course, many people just reenergize, not believing there is anything wrong, but at least someone is there for the next incident.

The traditional Buchholz relay is common for large conservator design transformers, but that can be much slower to detect a winding fault, even an arcing fault.

The sudden pressure protection is much more effective on transformers designed without conservators, tanks with limited gas space, as compared to tanks which allow for oil expansion. Conservator design transformers have been traditional in Europe and Canada. The Buchholz relay samples the oil to the expansion tank, looking for gas, which can produce some delay in operation, adding more energy to the fire.

It’s possible that this has all changed in the last 30 years, but this equipment is often used well past its typical design life of 50 years, so may still be applicable. :)

When I heard this sad news on the incident, few questions came to my mind!
1- was there any automatic shutdown unit based on control instrument system, safety critical elements, heat/vibration/smoke/fire detection/isolation trip system, etc. in place?

2- was there any emergency backup / standby unit in place!

3- Was there any preventive maintenance plan in place for continuous monitoring/checks/inspection/ critical spare units available!

4-Was there any human error involved or chance of a cyber attack on the unit?

5- was there safe spacing distance between various units like storage area/fuel tanks/flammable material storage/ignition sources/intrinsically safe items, units?

6- Was there any Structural Integrity Management System (SIMS) in place to identify potential load bearing steel structures which could loos their integrity if exposed to heat radiation/fire and was there any passive fire protection system for protection of such critical structure for approximately 15-30 minutes while operators can intervene & control the situation!

7-Was there any control room where operator could monitor the functionality/operability/maintainability of such critical units and follow the Standard Operating Procedure (SOP) in control room to manage/control the event? Was there any similar previous incidents at this unit and were the lessons learned implemented to prevent future recurrences?

these are just my initial thoughts, detailed investigation will obviously identify the Critical Factors/ Immediate Causes & Root Causes?

thanks & best wishes

I hate to mention this, but, I'm sure I won't be the first. Won't terrorists all over the world be looking at this as an easy way to cause total chaos?

Spot on - the bad guys are probably already surveying the substation all over the world. When we get the contract to design these stations we tend to concentrate on the technical and cost aspects, but nobody ever asks us to consider terrorist proofing the installation! Maybe it's time to create a new job description for this line of work and add it to the insurance cover.

Reminds me of an old 60s film, The Heroes of Telemark, which was based on the WW2 resistance efforts to prevent the production of heavy water to be used ion nuclear devices.

There's a scene in that where a resistance operative cycles into the countryside near the production plant then throws his cycle onto the transformers to short them out.

The terror idea is nothing new.

Of course, it is all part of the conspiracy to increase the numbers crossing the Channel in small boats...

...and another sells replacement transformers...

Perhaps young Jimmy needs to be more careful where he throws his Frisbee...

Heathrow bosses were warned of substation power failure risk days before electrical fire shut airport